Dental replacement parts, such as crowns, bridges, implants or the like, can be produced by first scanning the prepared tooth stump as a gypsum model using an optical or mechanical scanner, and then creating milling curves for the cavity of the tooth replacement part using the data obtained by the scanning. A wax prosthesis formed by the dental technician is then placed on the gypsum model of the stump and is scanned for obtaining additional data for generating the milling curve. Both sets of data represent in a coordinate system the volume to be milled. Alternatively, the tooth replacement placement part may already be present in digital form in standard libraries and adapted to the respective individual situation.
PCT publication No. WO 95/30382 discloses a device for holding blanks used in the production of dental replacement parts by a milling or other machining tool. For economical reasons, the tooth replacement blank is so dimensioned that the working results in minimum waste the expensive blank material. The generally cylindrical blank is glued into a cylindrical carrier body which surrounds the blank in a partial area of its axial length and is adapted to be inserted in the respective machine tool.
In the system disclosed in European patent publication No. 0 455 854, a tooth replacement blank is worked from a slab of material in such a way that both a tooth crown and a holding stump are created. Upon severing the crown, a bore of the crown is fitted on a conical end of the holding stump.
It is an object of the invention to provide a receptacle for a tooth replacement blank which serves not only for holding the blank in the respective machine tool but at the same time represents a primary package for protecting the blank and handling it safely in the course of an automatic production process.
This object is met in accordance with the invention by a device for producing a dental replacement part, including a blank and a carrier body, the carrier body having an inner side holding the blank and an outer side adapted to be fitted in a working tool, wherein the carrier body is dimensioned so that the blank does not extend beyond the carrier body in any direction.
The fact that the blank does not extend beyond the carrier body in any direction results in an effective protection of the blank material against mechanical influences. Moreover, the blank may be worked from two opposite sides, which is essential for tooth replacements. Since it is solely the carrier body which defines the outer shape of the unit formed by the blank and the carrier body, the carrier body may be designed without limitations in such a way that it may be stacked with other units irrespective of the exact shape of the blank and automatically fed, withdrawn and turned in the course of an automatic production.
In a preferred embodiment, the carrier body is substantially plate-shaped and has an opening for receiving the blank, the through length of the opening being not smaller than the axial dimension of the blank. The plate shape of the carrier body is particularly advantageous for handling and stacking.
The carrier body is preferably formed with a recess from at least one of its end surfaces to form a peripheral flange and a receiving cylinder surrounding the opening. The recess form ribs which extend radially between the peripheral flange and the receiving cylinder. This results in a high rigidity at low material consumption.
In accordance with another preferred embodiment, the peripheral flange defines the largest height of the carrier body and the receiving cylinder is recessed in both axial directions with respect to the peripheral flange. The overall dimensions of the carrier body are thus determined by its outer part, whereas its inner part surrounding the blank is smaller thereby rendering the blank readily accessible for the working tool.
Since the carrier body according to the invention may be designed substantially independently of the size and shape of the blank, it provides sufficient space for receiving a code related to the blank preferably to the dimensions and/or material thereof. The machine tool may be designed such that, by means of the code scanned from the carrier body, it automatically performs the proper process step with the proper tool for the blank contained in the carrier body, or suppresses the working step in case of non-coincidence.
Advantageously, the code is adapted to be changed by the working tool This prevents an inadvertent double working of the same blank. At the same time, this feature guarantees that only original blanks, as provided by the producer including the carrier body, are worked whereas used carrier bodies re-fitted with blanks, are rejected.
In yet another embodiment of the invention, the carrier body has a non-symmetrical outer shape to permit the carrier body including the blank to be properly oriented within the machine tool.
With a view to material expense and manufacturing costs, the carrier body is preferably formed of synthetic material by injection moulding.